Usage: syncfs [FILE...]
Force all pending disk writes to be done immediately
-s, --synchronous Wait for completion of all disk writes
-c, --no-children Do not synchronize child filesystems
-?, --help Give this help list
--usage Give a short usage message
-V, --version Print program version
The filesystem containing each FILE is synchronized, and its child
filesystems unless --no-children is specified. With no FILE argument
synchronizes the root filesystem.
Report bugs to bug-hurd@gnu.org.

The devprobe utility probes for one or multiple Mach devices.
Just specify the names as arguments on the command line: If some of the
devices exists it will echo their names one per line and exits successfully,
otherwise it will return 1. The provided options make it easier to use this
utility in batch mode.

Running "/bin/devprobe --help" gives:

Usage: devprobe DEVNAME...
Test for the existence of mach device DEVNAME...
-s, --silent Don't print devices found
-f, --first Stop after the first device found
The exit status is 0 if any devices were found.